Various devices and methods have been proposed as user interfaces for operating devices such as computers, game machines, and video telephone conference systems.
For example, in the information input device described in Patent Document 1, an infrared beam from an infrared transmitting unit of a pointer is transmitted simultaneously with an ultrasonic wave from an ultrasonic wave transmitter, and the position pointed at on a display by the pointer is input by the time difference of the time of receiving the ultrasonic wave, with respect to the time of receiving the infrared beam as a reference.
In the information processing device described in Patent Document 2, an image on an information input surface struck with light is captured, and information is processed in accordance with the position on the information input surface of an input device detected based on the intensity distribution of the captured image on the information input surface.